// Copyright 2017 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_TEX_COORDS_PORTABLE_ENCODER_H_
#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_TEX_COORDS_PORTABLE_ENCODER_H_

#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_encoder.h"
#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_tex_coords_portable_predictor.h"
#include "draco/core/bit_coders/rans_bit_encoder.h"

namespace draco {

// Prediction scheme designed for predicting texture coordinates from known
// spatial position of vertices. For isometric parametrizations, the ratios
// between triangle edge lengths should be about the same in both the spatial
// and UV coordinate spaces, which makes the positions a good predictor for the
// UV coordinates. Note that this may not be the optimal approach for other
// parametrizations such as projective ones.
template <typename DataTypeT, class TransformT, class MeshDataT>
class MeshPredictionSchemeTexCoordsPortableEncoder
    : public MeshPredictionSchemeEncoder<DataTypeT, TransformT, MeshDataT> {
  public:
    using CorrType = typename MeshPredictionSchemeEncoder<DataTypeT, TransformT,
          MeshDataT>::CorrType;
    MeshPredictionSchemeTexCoordsPortableEncoder(const PointAttribute *attribute,
            const TransformT &transform,
            const MeshDataT &mesh_data)
        : MeshPredictionSchemeEncoder<DataTypeT, TransformT, MeshDataT>(
              attribute, transform, mesh_data),
          predictor_(mesh_data) {}

    bool ComputeCorrectionValues(
        const DataTypeT *in_data, CorrType *out_corr, int size,
        int num_components, const PointIndex *entry_to_point_id_map) override;

    bool EncodePredictionData(EncoderBuffer *buffer) override;

    PredictionSchemeMethod GetPredictionMethod() const override {
        return MESH_PREDICTION_TEX_COORDS_PORTABLE;
    }

    bool IsInitialized() const override {
        if (!predictor_.IsInitialized())
            return false;
        if (!this->mesh_data().IsInitialized())
            return false;
        return true;
    }

    int GetNumParentAttributes() const override {
        return 1;
    }

    GeometryAttribute::Type GetParentAttributeType(int i) const override {
        DRACO_DCHECK_EQ(i, 0);
        (void)i;
        return GeometryAttribute::POSITION;
    }

    bool SetParentAttribute(const PointAttribute *att) override {
        if (att->attribute_type() != GeometryAttribute::POSITION)
            return false;  // Invalid attribute type.
        if (att->num_components() != 3)
            return false;  // Currently works only for 3 component positions.
        predictor_.SetPositionAttribute(*att);
        return true;
    }

  private:
    MeshPredictionSchemeTexCoordsPortablePredictor<DataTypeT, MeshDataT>
    predictor_;
};

template <typename DataTypeT, class TransformT, class MeshDataT>
bool MeshPredictionSchemeTexCoordsPortableEncoder<DataTypeT, TransformT,
     MeshDataT>::
     ComputeCorrectionValues(const DataTypeT *in_data, CorrType *out_corr,
                             int size, int num_components,
const PointIndex *entry_to_point_id_map) {
    predictor_.SetEntryToPointIdMap(entry_to_point_id_map);
    this->transform().Initialize(in_data, size, num_components);
    // We start processing from the end because this prediction uses data from
    // previous entries that could be overwritten when an entry is processed.
    for (int p = this->mesh_data().data_to_corner_map()->size() - 1; p >= 0;
            --p) {
        const CornerIndex corner_id = this->mesh_data().data_to_corner_map()->at(p);
        predictor_.template ComputePredictedValue<true>(corner_id, in_data, p);

        const int dst_offset = p * num_components;
        this->transform().ComputeCorrection(in_data + dst_offset,
                                            predictor_.predicted_value(),
                                            out_corr + dst_offset);
    }
    return true;
}

template <typename DataTypeT, class TransformT, class MeshDataT>
bool MeshPredictionSchemeTexCoordsPortableEncoder<
DataTypeT, TransformT, MeshDataT>::EncodePredictionData(EncoderBuffer
        *buffer) {
    // Encode the delta-coded orientations using arithmetic coding.
    const int32_t num_orientations = predictor_.num_orientations();
    buffer->Encode(num_orientations);
    bool last_orientation = true;
    RAnsBitEncoder encoder;
    encoder.StartEncoding();
    for (int i = 0; i < num_orientations; ++i) {
        const bool orientation = predictor_.orientation(i);
        encoder.EncodeBit(orientation == last_orientation);
        last_orientation = orientation;
    }
    encoder.EndEncoding(buffer);
    return MeshPredictionSchemeEncoder<DataTypeT, TransformT,
           MeshDataT>::EncodePredictionData(buffer);
}

}  // namespace draco

#endif  // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_TEX_COORDS_PORTABLE_ENCODER_H_
